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wow this topic got way off . . . ummm . . . topic . . .QuoteSo my next project in mind is to create a simple microcontroller thingy with a ATmega644. I'm basing it off Admin's $50 robot, and some other tutorials I've seen online. If all goes well, I'll have something that will let me control servos and I/O from sensors relatively cheaply.hey! so im programming at ATmega644 now actually! we should collaborate somehow . . . the $50 robot is actually based off of what I learned with the 644 but i plan to have some really advanced/expensive features on it so its not the kind of thing beginners should ever attempt . . .
So my next project in mind is to create a simple microcontroller thingy with a ATmega644. I'm basing it off Admin's $50 robot, and some other tutorials I've seen online. If all goes well, I'll have something that will let me control servos and I/O from sensors relatively cheaply.
what kind of stuff are you doing with the 644?
I'm not an ECE major though, and I didn't take any ECE courses
a lot:wireless underwater uart data transmissionin-vitro reprogramming (bootloading)3 axis accelerometercurrent draw sensorpressure sensor2 axis gyrodigital compasscontrol of 21+ independent servosand a blinky LED Ive got about half of it working . . . probably the most advanced circuit and program Ive done for robotics yet . . .
You really should take a few ece classes. I took several as electives - very useful stuff! You should probably take intro to meche, too
Oh wow! That's a lot I'm just intending to do some servo controlling and sonar + zigbee probably.
1. Is it just a matter of connecting the RX and TX to an 7404N inverter, then to a serial connector?2. Do I need to worry about the voltage levels coming from the PC?
3. How will the software to read/write to the serial port be like?
I'm trying to figure out which pins support PWM.. I can't figure it out from the datasheet All I know is that there are 6 channels that do PWM, but not which 6
For the capacitors I use, does the voltage rating matter?
"will this work?"
You may find this helpful:http://www.societyofrobots.com/robotforum/index.php?topic=606.0(this was a question I had when I was wiring up my 644)
Put the .33uF cap on the out pin of the 5V regulator, otherwise it will just burn out the regulator faster when the cap is drained.
And Im guessing thats a 6V regulator on the 7.2V battery to power servos? BAD! It will overheat and stop working. Use a switching regulator, or a 6V battery. Expect each servo to drain ~.5A.
I am assuming that '20 Mhz' has a crystal and capacitors?
Lastely, on/off switches near your batteries is a must, and maybe a fuse too if you expect to drain high currents.
Hmm, do you mean switch the 0.33uF and 0.1uF caps, or add an additional .33uF to the out pin of the regulator?
Oh, the reason why I wanted to do this was because Whisk had issues with voltage dropping after running for a while. Will attaching a heat sink be sufficient? I was intending to put a heat sink on each of the voltage regulators.
Hmm, so the datasheet said the crystal was "series" and didn't have a capacitor listed, so I'm assuming it doesn't need one? Some other crystals by the same manufacturer had capacitances listed, but this one and a couple others didn't.. Here's the datasheet: http://www.ctscorp.com/components/Datasheets/008-0309-0_C.pdf
Yeap I was intending to have switches for the batteries. What amperage should I put a fuse at? Slightly higher than the max rating of the regulator, or double?
Hmm, so the datasheet said the crystal was "series" and didn't have a capacitor listed, so I'm assuming it doesn't need one?
For now, I left the 20 MHz crystal connected. If I don't use a crystal, do I just leave the pins unconnected, or do I short them? Regarding the capacitors for the crystal, it seems that a series crystal doesn't need external capacitors (http://www.foxonline.com/techdata.htm search for "Figure 3.0"), is that right?
So I was wondering, why not just add a crystal to make the IC go faster? Grin The internal clock goes at 8 MHz but a crystal can push it to 20 MHz, and extra speed for the cost of a crystal is worth it right? Power consumption goes up, but it shouldn't make too much of a difference right?
Also, I was looking at the switching regulators, and it seems that 5V is the closest I can get. 6V switching regulators don't seem to exist somehow.. Any ideas why?
I added a switch and fuse for each of the battery sources. The fuse ratings are just semi-random numbers for now, I haven't actually figured out what to put for each yet.
And I switched the 0.1 uF and 0.33 uF capacitors for the 5V regulator. I'm a little unclear about this part though. In the datasheet (http://www.st.com/stonline/products/literature/ds/2143/l7805c.pdf page 4 Figure 3), it shows the application circuit with 0.1 uF connected to the output pin, and 0.33 uF connected to the input pin.